Production of sulfate of ammonia



July A14, 1953 c, OTTO 2,645,560

PRODUCTION OF SUL-FATE OF' AMMONIA xNvENToR i CHQ/RL @T70 a. ATTORNEY July 14, 1953 c, OTTO 2,645,560

PRODUCTION OF SULFATE OF AMMONIA Filed March 18, 1950 i 3 Sheets-Sheet 2 xNvENTo'R CIQRL OTTO ATTORNEY July 14, 1953 c. OTTO PRODUCTION 0F SULFATE OF AMMONIA 3 Sheets-Sheet 3 Filed March 18, 1950 fgllaft.:2544::11|$15545251541141115.

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INVENTOR C'qRL OTTO ATTORNEY Patented July 14, l1953 UNITED STATES ETNT OFFICE PROBUC'IHON SULFATE OF AMMONIA Carl Otto, Manhasset, N. Y.

Application March 18, 1950, Serial No. 150,410

3 Claims.

. l The present invention relates tothe production of ammonia sulphate from gas, such as coke oven gas, having a small ammonia content, by spraying 4 liquor containing ammonia sulphate and sulfuric acid into a substantially unobstructive scrubbing chamber through which the gas is continuously passed at a relatively high velocity. In the preferred practice of the present invention I, make use of apparatus invented by me and disclosed in prior applications filed by me. Those applications include my application, Serial No. 720,593, iiled January 7, 1947, of which this application is a continuation in part, said application having been abandoned since the instant application was filed, and in my Patent No. 2,599,067, granted June 3, 1952, on my application, Serial No. 14,902. Said patent discloses and claims various forms of spray saturators for recovery of ammonia from coke oven gas disclosed alike in said patent, said application Serial No. 720,593 and herein.

The liquid sprayed into the scrubbing chamber is preferably a saturated solution of ammonium sulphate entraining previously formed ammonium sulphate crystals. In the scrubbing chamber, the ammonium sulphate solution becomes supersaturated as a result of the absorption of ammonia from the gas. The supersaturated liquor passing downward through the scrubbing chamber is collected in a crystallizing and desupersaturating bath space. The latter may be the bottom portion of the tank enclosing the scrubbing chamber, or it may be a chamber in a separate tank into which the first mentioned tank drains. Some of the supersaturated spray liquor inevitably impinges against the inner surface `of the tank wall and becomes part of a liquid nlm or layer on that wall. While that film tends to flow downward along the wall under the action of gravity, there is a tendency for ammonium sulphate to crystallize out of the liquor lm and adhere to the wall in the form commonly known as rock salt.

Spray saturator methods of and apparatus for producing sulphate of ammonia from coke oven gas disclosed and claimed in my prior applications. are now in successful commercial use. One of the maior advantages obtained in the use of such methods and apparatus, is a great reduction in the size and in the construction and operation casts cf the apparatus required to recover the i ammonia content of coke oven gas supplied at a given volumetric rate.

The high gas treating capacity of my spray saturators, is made possible, in large part, by the dispersim. f lh@ llbbllg lqllOr .in the form of very line particles in the scrubbing space, coupled with the relatively high linear velocity of the gas moving through the space. The high gas velocity and the ne vsubdivision of the spray liquor each tend to the entrainment of spray liquor in vthe gas passing out of the scrubbing chamber. Such entrainment of liquor in the gas passing away from the saturator through its gas outlet, is objectionable because the entrained liquor contains sulphuric acid. The cost of the sulphuric acid used is a major expense item in the production of sulphate of ammonia from coke oven gas and its waste is objectionable for that reason. Moreover, the entrainment of liquor in the gas leaving the saturator is lobjectionable because of the corrosive action of sulphuric acid on the metal piping and valves through which the gasleaving the saturator is passed.

A general object of the present invention is to provide improved means for separating entrained acid from gas passing away from the gas scrubbing chamber. Heretofore, it has been customary to separate entrained acid from the gas by passing the latter through a so called acid catcher external to the scrubbingr tank and usually in the form of a cyclone separator.

I have discovered, and believe i was fthe rst Y to realize, that it is practically feasible and advantageous to separate entrained acid from the scrubbed gas before it leaves the scrubbing tank. A primary object of the present invention is to provide a spray saturator with an effective and relatively simple and'inexpensive baille structure or screen, and supporting means therefor, between the scrubbing space therein and the Fas outlet therefrom, to screen out of the gas passing through the screen the maior portion of the liouor particles entrained in the gas coming into contact with the screen as it passes away from the scrubhing space and for returning the acid thus recovered into admixture within the satura-tor with the acidied ammonium sulphate solution collecting in or drainingr from the lower end of the saturator. The liquor thus arrested bv the screen eventually passes down through the scrubbing chamber and out of the latter with the ammonium sulphate licuor and crystals passing away from the scrubbing chamber at the lower end of the latter.

.Another important object of the present invention is the provision of simple and eiective means for keeping the acid catching screen or baille structure clean and suitably pervious.

A more specific object of the invention is to provide an acid catching screen or baille structural arrangement which can be kept clean and eiectively pervious by spraying cleaning liquid usually consisting wholly or largely of hot Water onto said structure and which will pass a large portion of the cleaning liquid structure into Contact with the vertical wall surrounding the scrubbing space. The hot cleaning liquid thus passed into contact with the vertical scrubbing space wall, will flow down that wall in the form of a layer or lm and will mix with supersaturated spray liquor impinging against the wall, and will serve the useful purpose of diluting that liquor and preventing it from depositing ammonium sulphate on the wall in crystalline or rock salt form.

The various features of novelty which characterizes my invention are pointed out` with particularity in the claims annexed to and forming a part' of this specication. Fora better-understanding of the invention, however, its advantages, and specic objects attained with its use, reference should be had to the accompany- .ing drawing and `descriptive matter in 'which I Fig. 3 is a plan view showing a flat blank to be A bent into a baffle part used in Fig. 1;

Figs. 4 and 5 are partial sectional elevations of a spray saturator each showing a differ-ent' modification ofthe acid-catcher structure shown in g- Fig. 1;

Fig. 5a is an inverted plan section on the line 5-5 of Fig. 5;

Fig. 6 is a sectional elevation-of a portion of .a spray saturator showing a third acid-catcher modication;

Fig. 6a is a partial section on the line ea-6a of Fig. 6;

Fig. 6b is a side elevation on an enlarged side Of a portion of the acid-catcher shown in Figs.

Fig. '7 is a sectional elevation of a portion of a spray saturator showing a fourth 4acid-.catcher modification;

Fig. 7a isa partial section on the line a-Ta of Fig. 7;

Fig. 8 is a sectional elevation and Fig. 8a -is an inverted plan of a portion vof a spray saturator illustrating e. fth acid-catcher modification.

In Fig. l, I have illustrated by way of example, an embodiment of the present invention in a ,spray saturator which is of a type and yform disclosed in each of said prior applications, No. '720,593 and No. 14,902. The saturator shown in Fig. 1, comprises a vertically disposed tank l having a cylindrical body portion surrounding a scrubbing ,chamber .2 and having a hopper bottom and a depending coaxial liquor outlet pipe 3. The coke oven gas scrubbed i-n the charnber 2, enters the tank through a lateral gas inlet 4 opening into the cylindrical portion of the tank adjacent the lower end of thelatt'er. The scrubbed gas passes away from the tank through a lateral gas outlet 5 formed in the cylindrical body portion of the tank adjacent the upper end of the tank. The pipe 3 extends down int'o a receptacle 6, open to the atmosphere at its upper end and having its bottom wall but slightly below the lower end of the liquor outlet pipe 3. The receptacle 6 is substantially larger in diameter of the tank I.

than the pipe portion 3, so that the latter is surrounded by an annular chamber 'I open at its upper end and of substantial capacity.

The chamber 1, and the bore of the pipe 3 collectively form a crystallizing space in which the liquor supersaturated in the scrubbing chamber is desupersaturated, and thereby promotes the growth of crystals of ammonium sulphate crystals formed in the crystallizing space and passing into the latter with the liquor passing downward out of the scrubbing space 2. The wall of the receptacle 6 is made hollow to provide a steam jacket heating space 8 for said chan-1- ber. Similarly, the outlet pipe 3 is formed with adouble Wall to provide an annular steam jacket heating space 9. The body portion of the tank shell is surrounded for the major portion of its length by a steam jacket heating space It. The purpose of said steam jacket spaces is to increase the temperature of the liquor wet walls and thereby prevent the formation of rock salt deposits on said walls.

Liquor and entrained crystals are withdrawn 'from the crystallizing space 'I at an upper level,

by a Vpump `I'I which passes the liquorinto the `scrubbingchamber 2 through a spray nozzle i2 carried by the .depending outlet end portion of the pump outlet pipe I 3. A depending outlet end portion of the pipe I3 passes centrally into the upper end of the chamber 2 through the top wall plate I4 of the tank I. Make-up acid may be 'passed into the inlet or" the pump II through a valved pipe I5. As shown, the inlet of the pump H is connected to a ring shaped trough I6 eX- tending horizontally around the vertical pipe 3. Liquor overflows 'from the crystallization receptacle 6 Ythrough an overflow pipe Il which discharged into a tar separator chamber I8. The latter is provided with a valved tar outlet i9. The tar separator chamber i8 is surrounded by the wall of a tank 20 and is separated from a clear liquor chamber 2I by a vertical tank portion 22 which does not extend to the bottom of the tank 20. rI'he latter has a hopper bottom 23 terminating at its lower end in an outlet 24 connected to the inlet of a pump 25. The latter returns liquor to the upper end of the chamber 'I throughA a pipe 25.

A pump 2l drawing liquor from the clear liquor chamber 2'I of the overow tank 20 has a discharge pipe 29 with a valve 2B therein through which liquor may be passed to a spray ring Si) when the valve 28 is open. rIhe spray ring 39 is carried at the under side of the top plate I l Alternatively, with the valve 28 closed, hot water under pressure may be passed to the spray ring 30 through a valved hot water supply pipe 3| and the portion of the pipe 29 Vbetween the valve 28 and the spray ring 3d. If

iand when desired, the valve -28 and the valve in the hot water supply .pipe 3l may be adjusted to pass a mixture of hot water and liquor to the spray .ring 30. When it is desired to supply hot water only to the spray ring 30, the pump 2"! may be omitted. A second pump 32 draws liquor 'from the clear liquor chamber 2! of the tar decanter 20 and discharges it into the lower portion of the scrubbing chamber -2 through a spray nozzle 33 mounted in the inlet 4. Hot water may also be passed to the nozzle 33 through a valved pipe 34.

The spray ring 30 discharges liquid against the upper portion of the inner wall of the tank I in the body of the tank I and of the superposed tank section 35 and against the outer surface of the portion of the pipe I3 extending downward from the under side of the top wall l 4 and against the acid-catcher bale or pervious wall A shortly to be described. The cross sectional area of the lower portion of the tank section 35 increases with the distance above the tank body, so that liquid sprayed onto the` upper end portion of the inside wall of the section 35 will flow along that' wall to the upper end of the inner wall of the tank body.

In accordance with the invention claimed herein, an acid-catcher A is arranged in the top of the scrubber tank to arrest and screen out of the gas passing from the scrubbing chamber 2 to the outlet Ei, the maior portion, at least, of the liquor entrained in the gas passing out of the scrubbing space into the acid-catcher. The latter may be formed of baiie plates -or grids formed of material resistant to the corrosive action to which they will be subjected by the sulphuric acid content of the entrained liquor, such as wood, ceramic pieces in various forms including ribbed Plates, the ilanged parts known as Berl saddles and the short tubular sections or parts known Raschig rings, or parts of metal such as Monel metal or stainless steels not subject to attack by dilute sulphuric acid. Regardless of the baille or grid material used, the acid-catcher is preferably so formed that a relatively large portion of the liquid sprayed onto the acid-catcher and cleaning the latter, is discharged by the acid-catcher against the adjacent wall of the scrubber tank, and is added to the liquid layer or nlm flowing downward along the inner side of that wall. The cleaning liquid thus added to the down iiowng nlm on the inner side of the tank wall, decreases the sulphate percentage or content of the film, and increases the thickness of the nlm 4of the liquid therein and thus substantially reduces the tendency for sulphate crystals to deposit on and adhere to the tank wall in the form of rock salt.

The acid-catcher construction A illustrated in Figs. 1, 2 and 3 comprises superposed sheets 35 of Monel metal or stainless steel in expanded metal form of the conventional type, made by slitting and stretching actions in accordance with the disclosure of Patent 527,242 of October 9, 1904. Each expanded metal sheet t6 comprises 4bent portions and is substantially thicker than the at sheet from which the expanded metal is formed. As shown, each sheet 35 is bent into the shape of an inverted V with a attened apex portion 3l. The metal. sheets 9,5 are nested together to form the acid-catcher A shown in Figs. l and 2. The acid-catcher A forms a roof for the scrubbing chamber having similar steeply inclined diverging portions integrally connectedl by the superposed horizontal portions il of the different sheets which collectively form a iiattened ridgepole portion of said roof. Each acid-catcher sheet or layer 35 may -be formed by a simple bending operation from a nat blank of the form shown in Fig. 3. That blank comprises similar sections 38 of an eclipse at opposite sides of and integrally connected to the horizontal central portion 3l' of the blank. As will be apparent, the length of the portion 3S of the major axis or said eclipse in each section 33 increases as the angle of inclination to the horizontal of each sloping portion of the axis catcher A increases. As shown, each baiile layer 3d is formed with a central aperture 35 for the passage therethrough o the depending pipe I3 shown in Fig. 1.

The acid-catcher A of Fig. l may be supported in any usual or suitable manner, as by means of a horizontal beam 4c which is directly beneath the ridge-pole portion of the acid-catcher, and is welded at its ends to the tank. Alternatively, or in addition, lugs or flanged bar sections fil welded to the tank wall may be arranged to engage and directly support the lower edge ofthe lowermost balile plate 3c in the general manner indicated in Figs. 1 and 2. A sleeve l2 surrounds the pipe i3 and acts between the end wall l/l and the top of the baille wall A to prevent any lifting of the plates 35, as a result of the increase in the gas pressure in scrubbing chamber 2 over the gas pressure above the baiiie wall, which ordinarily can occur only when the normal supply of cleaning liquid through the pipe 29 and spray ring 3i! is interrupted and the interstices in the baiile wall are allowed to clog up.

The spray ring 39 is preferably so formed and arranged that the maior portion of the hot water or other cleaning liquid which it discharges will impinge against the upper surface of the acid catcher A. With the relatively steep inclination of the inclined wall portions of the acid catcher, much of the liquid sprayed onto the upper side of the acid catcher A will flow in lrn form along the various acid catcher plates 35 into engagement with the inner wall of the tank i, and will then form part of the liquid lm or layer owing downward along the inner wall ofthe tank.

As previously indicated, the acid catcher may take various forms different from that shown in Figs. 1, 2 and 3, some of which are shown in Figs. 4 8.

Thus in Fig. Zl, an acid catcher A4 comprising a pervious baiiie wall is arranged between the axis of the tank and the gas outlet 5, with its edge in engagement with an upper portion of the tank wall body and a lower portion of the tank upper end section 35, along a continuous line surrounding and displaced from the outlet opening. In the particular arrangement shown in Fig. 4, the pervious baille Wall comprises a vertical intermediate section it and lower and upper sections i3d and Liib. The sections (53a and 13b are reversely inclined to the vertical away from the axis of the tank i. As shown, the sections t3 and 43a form horizontal chords extending across upper portions of the tank body, and the section zlib forms a horizontal chord extending across the lower portion of the tank section 35. Each of the sections 123, 43a, and -b may be composed of wooden grids or acid proof tiles. As shown, the end edges of the chord like sections are held in place between separate metal flanges or ribs lill and A5. The ribs All and l5 engaging the sections A3 and ita are welded to the body of the tank wall, and the ribs All and 45 associated with the chord like section 3b are welded to the tank end section 35. Wooden laths, and small ceramic parts included in the bafiie wall A4, may be supported between the wall edges by parts it at each side of the wall. The latter may consist of a sheet of expanded metal, or bars i6 arranged in sideby-side Vertical plane-s transverse to the chord like sections 53, -Sc, and 43D, or by both said sheets and bars. The endslof the parts fit adjacent the upper edge of the section 43 and the lower edge of the section @3b may .be attached or supported by beams or bars il extending longitudinally of said sections and welded at their ends to the tank body or to the tank section 35. As shown, cleaning liquid may be sprayed against the side of the baiile wall A4 through a spray nozzle i9- receiving the liquid through a branch 29 of the pipe 29.

As shown, Vthe wall area of the acid catcher A4 is substantially smaller than that of the acid catcher A, and if it is generally similar in the character of its construction to the acid catcher A, the acid catcher A4 will oler substantially more resistance to gas flow through it than does the acid catcher A. As will be apparent, however, the area transverse to the direction of gas flow through each of the dillerent acid catchers shown is several times the cross sectional area of the outlet lpassage 5. In consequence, each of said acid catchers may be so formed that the aggregate cross sectional area of its interstices which collectively form the gas passage through the acid catcher, is substantially greater than the cross sectional area of the gas outlet 5.

The acid-catcher A5 shown in Figs. 5 and 5a is in the form of a flat pervious wall inclined to the horizontal and extending across the entire cross section of the tank I, and comprising wooden grids or acidproof tiles. As shown, the acid-catcher A5 rests on a grating 5D of Monel metal or stainless steel comprising a rim portion which when projected on a horizontal plane as shown in Fig. 5a appears to be circular but which is actually elliptical and comprising parallel sideby-side bars 5I having their ends integrally connected to the rim portion of the grating. Advantageously, and as shown, the bars 5I are inclined to the horizontal at the same angle as the baffle Wall A5. The rim of the grating 50 rests on lugs 52 welded to the wall of the tank I. As shown, a grating 50a, which may be similar to the grid 50 rests on top of the baille wall A5. To prevent laths or tile forming the wall A5 from lifting under adverse operating conditions, a strut 53 is interposed between the upper portion of the rim of the grating 50a, and the removable upper tank head 35a of the tank I, which is secured to the upper end of the tank body. When the head 35a is removed,` the wall A5 may be removed for cleaning or repairs and to give access to the subjacent spray nozzles.

If the acid-catcher A5 shown in Fig. 5 is formed of rsuperposed sheets of expanded Monel metal or stainless steel, as it may be, each sheet will be of elliptical shape. In the arrangement shown in Fig. 5, the downwardly directed upper liquor spray nozzle I2 is located centrally in the tank I, and may be vconnected to a vertical branch of the pipe I3 extending down through the tank top wall 35a and baille wall A5. As shown, however, the nozzle I2 is supplied with spray liquor through a portion of the pipe I3 which extends into the tank through the vertical wall of the latter.

With the arrangement shown in Figs. 5 and 5a, most of the cleaning liquid sprayed onto the upper side of the baille wall A5 and draining along and through the latter, passes into contact with the portion of the tank Wall adjacent the lower portion of said baille wall. However, the amount of cleaning liquid reaching the tank wall at the opposite side of the tank from the outlet 5 may be suitably increased by spraying jets of hot water cleaning liquid against the under side of the upper portion of baille wa1lA5 and the subjacent portion of the tank wall through one or more spray nozzles 54, supplied with liquid through piping 55 connected to the pipe 29.

In Figs. 6, 6a and 6b, I have illustrated an acid catcher A5 comprising a pervious wall of conical form which has the advantage of uniformity distributing about the axis of the tank I, the liquid The conical wall of the acid catcher A5 may be formed and supported in various Ways. In particular, it may be built up as-the conical roof portions of furnaces and cisterns sometimes are of plate like partsBI preferably perforated and arranged in successive courses 62 at successively higher levels and of successively smaller diameter. The plate like parts 6I may have their ends oppositely beveled and be formed with transverse ribs A53 to space the parts in different courses away from one another. The parts GI may be formed of wood, or of acid resistant ceramic material, or of metal. The latter may be in expanded form or may be in the form of ribbed plates which are preferably perforated. A tubular strut 64 surrounding the depending section of the pipe I3 and acting between the top plate I4 and the top of the conical wall A6. The lower course 62 of parts 6I is supported by a circular ilange or rib 55 welded to the tank wall.

In Figs. 7 and 7a, I have illustrated an acid catcher A'I in the form of a pyramid comprising inclined rafters or beam parts ll) which may be made of expanded Monel metal or stainless f steel, and are located at the corner edges of the pyramid, and on which sections 'II of expanded Monel metal or ribbed ceramic plates, arranged as shown in Figs. 7 and 7a, may be arranged of superposed courses l2. Each upper course in Fig. 7 overlaps the immediately subjacent course, as is the case in Figs. 6 and 6a. also.

In Figs. 8 and 8.a, I have illustrated a modirlcation of the apparatus shown in Fig. l in which the acid catcher baille wall A8 is horizontal and comprises a multiplicity of bent plates 8| arranged side-by-side to provide a plurality of zigzag passages leading from the bottom to the top of the baille wall. The plates 8l rest on a lower grating 82 comprising a circular rim portion and integrally connected across bar portions 83. The rim portion of the grating is supported on a circular llange 84 welded to the inner wall of the tank body I. A grating 82a rests on top of the baille wall A8 and is pressed against the baille wall by a beam 85 and a vertical tubular strut 86 which surrounds the pipe I3 supplying spray liquor to the spray nozzle I2. The lower end of said strut engages the beam 85, while its upper end s externally threadedand is surrounded by a nut 36a which abuts-against the lower side of the upper end head I4b of the tank. A plurality of hot water supply pipes 8l extend down through the tank top plate Mb and carry spray nozzles 88 at their lower ends. The pipe I3 extends far enough down into the tankto permit the horizontal baille wall A8 to be below the level of the under side of the gas outlet 5. The plates 8I,

- gratings 82, and associated parts for securing the baille wall A8 in place may all be formed of Monel metal or acid resistant stainless steel. The plates 8| may be impervious in some cases, but advantageously are formed of expanded metal, and are of the character of the pervious masses or hurdles employed in a so called hurdle washer of the type shown in the Biemann et al. patent, 2,003,271, of May 28, 1935.

The baille wall construction shown in Figs. 8 and 8a form a simple and ellective arrangement for screening entrained acid out of the gas passing from the scrubbing chamber to the gas outlet, but lacks the capacity for passing a relatively large portion of the cleaning liquid sprayed onto it to the surrounding tank wall.

The plates of Monel metal or stainless steel included inthe Various pervious baille walls illustrated arrangements and hereinbefore described,

may well have a thickness of from 1/8" to 1A"- In each of the forms of construction shown, the baffle wall is readily removable when necessary or desirable for cleaning, inspection, repairs, or to permit access to the scrubbing space beneath the wall.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. An apparatus for scrubbing ammonia out of coke oven gas with scrubbing liquid consisting mainly of ammonium sulphate solution contain,- ing ammonium sulphate crystals having a sulphuric acid content, comprising an elongated vertical scrubbing structure having an inlet gas conduit in the lower portion of said structure whereby gas in introduced above the liquid level and having an upper gas discharge conduit, said structure opening into a crystallizing chamber below said structure, said crystallizing chamber having an upper liquid conduit discharging through a spray nozzle into the upper portion of said structure, a conduit in the lower portion of said crystallizer for removing crystals, a tar separator near said crystallizer and a conduit from the upper portion of said crystallizer to the upper portion of said tar separator, a conduit from said tar separator to the upper part of said chamber above said spray nozzle, and a bafe in the upper portion of said chamber opposite the gas outlet conduit and between the spray nozzle and the conduit opening from the separator.

2. In removing ammonia from a stream of coke oven gas flowing upwardly through a substantially unobstructed scrubbing space in a scrubber which encloses said space and has a lower gas inlet above the liquid level and an upper gas outlet from said space, the method which consists in spraying ammonium sulphate solution with entrained crystals containing sulphuric acid into the ammonia containing gas in said scrubber space so that the gas only encounters spray of ammonium sulphate solution, separating said entrained solution by passing the gas through a baie after it is passed through the solution spray, said baie being washed by hot water and ammonium sulphate solution, allowing the solution t0 descend after contact with the gas into a crystallizing bottom portion oi' said space, withdrawing solution containing fine crystals from the upper part of said crystallizing space portion, adding sulphuric acid thereto and returning said solution to the scrubbing space as said spray.

3. In removing ammonia from a stream of coke oven gas iiowing upwardly through a substantially unobstructed scrubbing space in a scrubber which encloses said space and has a lower gas inlet and an upper gas outlet from said space, the method which consists in spraying ammonium sulphate solution with entrained crystals containing sulphuric acid into the ammonia containing gas in said scrubber space so that the gas only encounters spray of ammonium sulphate solution, separating said entrained solution by passing the gas through a baiile after it is passed through the solution spray, allowing the solution to descend after contact with the gas into the bottom of a crystallizing space, withdrawing crystals from the bottom of said space, circulating the solution containing ne crystals through a tar separator and returning said separated solution back to the crystallizing space, wihdrawing solution containing iine crystals from the upper part of said crystallizing space, adding sulphuric acid thereto and returning said solution to the scrubbing space as said spray.

CARL OTTO.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 824,092 Brunch June 26, 1906 1,673,732 Brooks June 12, 1928 1,713,045 Jacobson May 14, 1929 1,866,443 Zumbro July 5, 1932 2,354,675 Fisher Aug. 1, 1944 2,375,922 Jeremiassen May 15, 1945 2,482,643 Tiddy Sept. 20, 1949 

2. IN REMOVING AMMONIA FROM A STREAM OF COKE OVEN GAS FLOWING UPWARDLY THROUGH A SUBSTANTIALLY UNOBSTRUCTED SCRUBBING SPACE IN A SCRUBBER WHICH ENCLOSES SAID SPACE AND HAS A LOWER GAS INLET ABOUT THE LIQUID LEVEL AND ANN UPPER GAS OUTLET FROM SAID SPACE, THE METHOD WHICH CONSISTS IN SPRAYING AMMONIUM SULPHATE SOLUTION WITH ENTRAINED CRYSTALS CONTAINING SULPHURIC ACID INTO THE AMMONIA CONTAINING GAS IN SAID SCRUBBER SPACE SO THAT THE GAS ONLY ENCOUNTERS SPRAY OF AMMONIUM SULPHATE SOLUTION, SEPARATING SAID ENTRAINED SOLUTION BY PASSING THE GAS THROUGH A BAFFLE AFTER IT IS PASSES THROUGH THE SOLUTION SPRAY, SAID BAFFLE BEING WASHING BY HOT WATER AND AMMONIUM SULPHATE SOLUTION ALLOWING THE SOLUTION TO DESCEND AFTER CONTACT WITH THE GAS INTO A CRYSTAALLIZING BOTTOM PORTION OF SAID SPACE, WIHTDRAWING SOLUTION CONTAINING FINE CRYSTALS FROM THE UPPER PART OF SAID CRYSTAL- 